Help With Z'd Frame or Crossmember

[AfterThoughtVideo]

alright so I'm looking to get my long box to lay rocker, it's bagged already..now I dont have the time/space or really weld skills to do get it to lay rocker so I'm going to take it to my friends shop, but I have a few questions...want to get as much info before I drop it off at the shop

-Whats better Zing the frame 4'' or notching the exsiting crossmember 1.5''? and why?
-What problems or disadvantages or anything will occur with doing either of these and how will I fix or prevent these problems if there is any?
-How long will each take rough estimate? because he charges by the hour..
-Or whats an idea on a cost a shop would charge for this with the trans tunnel and everything...truck has a 305 motor in it, not sure if he'll have to do any modifying or raising to make sure the hood will shut

thanks!